Abstract
Background: Therapeutic success of thermal ablation for liver tumors depends on precise placement of ablation probes and complete tumor destruction with a safety margin. We investigated factors influencing targeting accuracy and treatment efficacy of percutaneous stereotactic image-guided microwave ablation (SMWA) for malignant liver neoplasms.Materials and methods: All consecutive patients treated with SMWA for malignant liver tumors over a 3-year period were analyzed. A computed tomography-based navigation system was used for ablation probe trajectory planning, stereotactic probe positioning, and validation of probe positions and ablation zones. Factors potentially influencing targeting accuracy [target positioning error (TPE)] and treatment efficacy within 6 months [ablation site recurrence (ASR)] were analyzed in a multivariable regression model, including challenging lesion locations (liver segments I, VII, and VIII; subphrenic location).Results: Three hundred one lesions (174 hepatocellular carcinomas, 87 colorectal liver metastases, 17 neuroendocrine tumors, and 23 others) were targeted in 191 interventions in 153 patients. The median TPE per ablation probe was 2.9 ± 2.3 mm (n = 384). Correction of ablation probe positions by repositioning was necessary in 4 out of 301 lesions (1%). Factors significantly influencing targeting accuracy were cirrhosis (R 0.67, CI 0.22–1.12) and targeting trajectory length (R 0.21, CI 0.12–0.29). Factors significantly influencing early ASR were lesion size >30 mm (OR 5.22, CI 2.44–11.19) and TPE >5 mm (OR 2.48, CI 1.06–5.78). Challenging lesion locations had no significant influence on targeting accuracy or early ASR.Conclusions: SMWA allows precise and effective treatment of malignant liver tumors even for lesions in challenging locations, with treatment efficacy depending on targeting accuracy in our model. Allowing for many tumors to be safely reached, SMWA has the potential to broaden treatment eligibility for patients with otherwise difficult to target tumors.
Highlights
For patients with malignant liver tumors, thermal ablation is a locally destructive, low-morbidity, and potentially curative treatment option, for hepatocellular carcinoma (HCC) and colorectal liver metastases (CRLM) [1, 2]
A maximum of five lesions were treated in one intervention to limit overall intervention time and generally lesions up to 5 cm in diameter were included for stereotactic image-guided microwave ablation (SMWA)
In 3 years, a total of 301 lesions were treated with SMWA in 191 interventions in 153 patients
Summary
For patients with malignant liver tumors, thermal ablation is a locally destructive, low-morbidity, and potentially curative treatment option, for hepatocellular carcinoma (HCC) and colorectal liver metastases (CRLM) [1, 2]. The crucial factor for successful ablative treatment is complete tumor ablation with an adequate safety margin [9], while avoiding injury to critical intrahepatic and perihepatic structures This is highly dependent on the precision with which the ablation probes are guided toward and positioned within the target lesions to subsequently generate adequate ablation zones. Safe percutaneous targeting is often precluded when using conventional ultrasonography (US) or computed tomography (CT) guidance [10], especially for tumors located in challenging intrahepatic positions such as in the liver dome [11], in a subcapsular location, or in proximity to the liver hilum or heart [12] Ablation of such difficult to target tumors results in an increased risk of complications and associated higher recurrence rates [13, 14], especially if multiple re-positionings of ablation probes are necessary to achieve adequate probe positions. We investigated factors influencing targeting accuracy and treatment efficacy of percutaneous stereotactic image-guided microwave ablation (SMWA) for malignant liver neoplasms
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